A Complex and Delicate Biochemical Process
Mouldy cheese, such as Gorgonzola in particular, are obtained through the use of selected strains of moulds, which spread into the cheese promoting the formation of the characteristic greenish-blue veining, and, as a consequence of their metabolism, the development of the aroma compounds that define the distinct taste, smell and “noble” aroma of this cheese.
Gorgonzola is a soft-texture mouldy cheese obtained from pasteurised whole cow’s milk to which lactic acid bacteria and selected moulds of the Penicillium roqueforti species are added.
In accordance with the approved Product Specification, the production method involves the pasteurisation of milk and the use of a natural milk starter consisting of thermophilic lactic bacteria.
The typical marbling of mould growth is obtained by adding selected Penicillium roqueforti spore cultures to the milk. During the maturing phase, the cheese is regularly pierced to promote the passage of air, which is necessary for the development of the Penicillium roqueforti mycelium.
The formation of the mould is the most distinctive trait of Gorgonzola cheese.
The maturing of Gorgonzola is the result of various biochemical processes which are carefully controlled through a dedicated production and maturing technology and lead to the modification of the curd constituents and the formation of new characteristic compounds.
The biochemical processes that occur during the maturing of Gorgonzola are rather complex. In particular, in Gorgonzola cheese, a varied and heterogeneous microbial flora contributes to the maturing of the cheese and the development of its characteristic aroma. The enzymatic activity of the microflora causes complex chemical transformations in the various curd components.
If the lactic microflora in the selected starter culture has the key task of producing the acidity required for the cheese-making process to take place correctly, the most important element in the maturing of Gorgonzola cheese is Penicillium roqueforti.
Acidity levels, which are high to begin with, are gradually neutralised by the formation of moulds during the maturing process.
Curd proteins are largely hydrolised, promoting the formation of high amounts of nitrogen compounds with a lower molecular weight. Free amino acids, in particular, grow continuously. From their partial breakdown, resulting from deamination and decarboxylation processes, new compounds originate.
The increase in the soluble nitrogen fraction with a lower molecular weight is connected to the formation of the characteristic aroma of Gorgonzola cheese: indeed, it is during the second stage of the maturing process, that is after approximately 40-45 days, that the typical flavour of this cheese begins to appear.
Lipids, largely hydrolised through the lipases produced by Penicillium roqueforti, release different amounts of fatty acids, which, in turn, create the necessary basis for other enzymatic transformations, releasing a series of volatile compounds such as methyl ketones (heptanone and nonanone).
Compared to other cheeses, proteolysis and lipolysis in Gorgonzola are particularly intense, resulting into the formation of the typical aroma of this cheese.
In a nutshell, with regard to the pungent smell of Gorgonzola, we can conclude by saying that the distinct flavour and smell of this cheese is caused by the characteristic aroma compounds that form during its maturing process.